During the past year, the molecular hematology laboratory of DLM completed validation of a quantitative BCR-ABL assay performed using real-time PCR methods. In reviewing our experience in parallel samples, we found excellent agreement between our previous method (nested qualitative PCR) and a quantitative real time assay, except in weakly positive samples. In these cases there were sometimes discordant results without a clear pattern of increased sensitivity for one method over the other. Since qPCR gives useful insights concerning the magnitude of residual disease not available using the qualitative assay, it was adopted as the standard for molecular monitoring of CML in February 2004. For research purposes, in collaboration with Dr. Barrett?s laboratory in NHLBI, we have used the assay to monitor the relationship between changes in minimal residual disease and the level of leukemia-antigen specific T cells in patients undergoing DLI and other forms of immunotherapy. These efforts should yield publishable results within the next year. We have also developed a quantitative PCR assay for measuring levels of WT1 RNA in blood and bone marrow. Since WT1 is expressed in many but not all common hematologic and epithelial tumors, this assay represents a useful tool both for identifying patients with WT1 positive malignancies suitable for WT1-directed immunotherapy, and as a marker for monitoring minimal residual disease. Studies in collaboration with other institute investigators to exploit this tool are under discussion.